My U.S. Pat. No. 3,816,659 issued June 11, 1974 for "Scanning Apparatus", which is now assigned to the assignee of this application, discloses an earlier apparatus suited to either the reading or writing of graphic and other indicia by a facsimile method, and the following patents refer to air or hydrostatic bearing systems:
Adams, U.S. Pat. No. 3,432,213, issued Mar. 11, 1969, for "Self-leveling Air Bearing Fixture".
Bruck, U.S. Pat. No. 3,806,208, issued Apr. 23, 1974, for "Hydrostatic Bearing Systems".
It is well-known that rotating bodies may be supported by air bearings. In such devices, the rotating body is supported by compressed air. It is also known that a brake may be applied to the rotating body in order to slow or stop its motion. However, in the prior art, the brake has been applied to the periphery of the rotating body in a direction perpendicular to the axis of the body. This, of course, may cause problems because when the body is stopped by the braking action, there is a tendency for it to strike the stationary supporting structure (from which the compressed air is ejected). In a system which requires a high degree of accuracy in the position of the rotating body over a period of years, it is very undesirable to have the rotating body engage the fixed support while the body is still in motion.